This invention relates to drop weight type impact testing machines.
Many machines have been developed in the past for testing materials. One approach has been to try and reproduce the type of failure which may occur to ensure that the materials being tested can withstand the forces and conditions they will encounter in use.
Recent earthquakes, both in California and Japan, have led to doubts about the reliability of testing apparatuses and procedures in place prior to those events. Failure of various structures occurred despite the fact that they were deemed to be "earthquake proof". One example is concrete structures, such as concrete columns and beams used on elevated freeways. Catastrophic collapse of these structures, with considerable loss of life and significant property damage, occurred despite the fact that some of the collapsed structures theoretically should have been capable of withstanding the forces of the earthquakes involved.
This has led to a demand for improved testing machines and procedures, particularly for concrete and reinforced concrete structures. There is a need to test relatively large concrete members for impact resistance. Many apparatuses have been designed in the past for impact testing, but are not suitable for testing such large concrete members with the high impact forces necessary. The amount of force involved in testing large concrete members can easily destroy a testing machine or even damage the foundation and building containing the machine.
Accordingly it is an object of the invention to provide an improved impact testing apparatus which overcomes disadvantages associated with earlier devices of the general type.
It is also an object of the invention to provide an improved impact testing apparatus which can withstand the high impact forces involved in impacting relatively large members of concrete or other materials without damage to the apparatus itself, its foundations or buildings housing it.
It is a further object of the invention to provide an improved impact testing apparatus utilizing a heavy impact hammer which can be raised above a specimen and easily released in order to be dropped on the specimen.
It is a still further object of the invention to provide an improved impact testing apparatus with a sliding impact hammer which can drop freely without binding.